(1) Field of the Invention
The present invention relates to low explosive compositions comprising about 45% to about 66% of a metallic nitrate, the balance being cellulose acetate, the percentages being by weight based on total composition weight. The invention further relates to igniters for ordnance devices such as artillery cartridges, grenades, land or sea mines and the like.
(2) Description of the Prior Art
A continuing objective in the design of ammunition, particularly for military use, is to provide an ammunition propellant that is energetic when used, but which displays low vulnerability to heat, flame, impact, friction and chemical action. This is especially important in confined quarters such as inside tanks, ships or the like.
To try to meet this objective, the so-called Low Vulnerability Ammunition (LOVA) propellants have been developed. These propellants typically contain about 75 to 80% by weight of a crystaline high explosive and about 20% to 25% by weight for an inert polyurethane binder. Typical high explosives used in LOVA propellants are cyclotetramethylenetetranitramine (HMX) and cyclotrimethylenetrinitramine (RDX).
Black powder, composed of sulphur, charcoal and a metallic nitrate, has been used for igniters, boosters, fuze trains, squibs, bursting charges and the like for hundreds of years. However, it has several severe drawbacks. It is a Department of Transportation Class A (Solid) explosive which makes shipping difficult. Also, it is difficult to control in manufacture and extremely hazardous to manufacture.
One use of black powder has been as an igniter for the propellant in artillery shells and the like. Quite often the propellant to be ignited is a LOVA propellant. Unfortunately, black powder is not a completely satisfactory igniter for LOVA propellants because it does not have low vulnerability characteristics itself.
Accordingly, it would be highly desirable to provide an explosive which is a substitute for black powder and which would be more energetic than black powder as an igniter, while at the same time exhibiting less vulnerability. The present invention provides such an explosive.